1. Field of the Invention
The present invention relates to a tape guide apparatus for use in a video tape recorder (VTR), and more particularly to a tape guide apparatus having a tape posture control pole for maintaining the posture of a video tape in a stable state.
2. Description of the Related Art
As is well known, a helical scan VTR is provided with both a front loading mechanism and a tape-loading mechanism. When a video tape cassette containing a video tape is horizontally inserted into the cassette insertion port formed in the front face of the VTR, the front loading mechanism receives and draws the cassette inside, and then lowers the cassette until it comes to the predetermined cassette-loading position. Thereafter, the tape-loading mechanism pulls the tape out of the cassette placed at the cassette-loading position and guides the tape such that it is in contact with about half of the circumference of the rotating cylinder. After the tape-loading mechanism sets the tape along the tape feed path in this way, various operation modes, such as recording, play, freeze (i.e., still image reproduction), slow play, fast-forward play, fast-rewind play, fast forward, and fast rewind, are selectively established with a mode-establishing mechanism and its associated circuits. If an eject key is operated, the tape-loading mechanism draws the tape back into the cassette, and the front loading mechanism returns the cassette from the cassette-loading position to the cassette insertion port.
FIG. 1 schematically illustrates the state in which the tape pulled out of the cassette is set along the tape feed path while in contact with the rotating cylinder.
As is illustrated in FIG. 1, the feed path of tape T extends from supply reel 1 of cassette C to take-up reel 9 thereof, by way of the following structural elements: tension pole 2; impedance roller 3; tape-pulling pole 4a; rotating cylinder 5; tape-pulling pole 4b; audio and control head 6; capstan shaft 7; and pinch roller 8. Pinch roller 8 is movable between a position at which it is pressed against capstan shaft 7 and a position at which it is located away from capstan shaft 7. More specifically, pinch roller 8 is pressed against capstan shaft 7 when tape T should be fed at a constant speed, and is moved away from capstan shaft 7 when tape T is rewound in the fast-rewind play mode.
A recently-developed VTR has not only an ordinary play function but also special play functions, such as a frame-feed slow play, a fast-forward play, and a fast-rewind play, and is therefore designed to feed tape T in both directions A and B indicated in FIG. 1 while simultaneously maintaining the image-reproducing function. The recently-developed VTR also has a high-speed search function, so as to quickly find the image the user wants to watch.
Tape cassette C has guide pins P1, P2 and P3 formed at tape-takeout ports. In general, these guide pins are not formed with high precision. In some cases, they are flimsy or are slightly titled, with respect to capstan shaft 7. Such flimsy or slanted guide pins are caused not only by their own low precision, but also because the main body of cassette C is formed of synthetic resin. Further, if cassette C is not guided accurately to the loading position, due to scratches or uneven portions thereof, it is likely that the guide pins will be slanted.
If the guide pins, particularly guide pin P1, are not accurately parallel to capstan shaft 7, tape T may not be fed from the supply reel or wound onto the take-up reel with a desirable posture.
Let it be assumed that the VTR is set in the fast-play mode, wherein pinch roller 8 and capstan shaft 7 are located apart from each other and wherein the tape is fed while being driven by the reels. If pin P1 is slanted in this case, tape T guided by pin P1 may slip in the widthwise direction thereof when it comes out of cassette C. If this happens, tape T will be shifted from the normal contact portion of rotating cylinder 5. Since rotating cylinder 5 has a stepped tape guide for guiding the tape edge, it is likely that tape T will be bent or damaged by the stepped tape guide.
Let it be assumed that the VTR is set in the fast-forward mode. If pin P1 is flimsy or slanted in this case, tape T may not be regularly wound onto take-up reel 9, leaving a gap between the adjacent turns of the wound tape. When tape T wound in this manner is used next, it may move in the widthwise direction when it is being fed, thus causing adverse effects on the rewind play mode of the VTR.